1. Field of the Invention
The present invention relates to a compact reactor, and more particularly, to a compact micro-macro channel reactor that efficiently obtains a target product through a catalytic reaction of a reactant by supplying a heat exchanging material and the reactant, effectively controls a reaction through exchange of heat between the reactant or the product and the heat exchanging material, and enhances the durability of the catalyst.
2. Discussion of Related Art
Generally, a reactor using micro channels (hereinafter, referred to as ‘a micro channel reactor’) has a structure in which a plurality of unit reactors each having a micro channel are stacked on each other. Such a reactor is compact and suitable for performing a chemical reaction such as a hydrocarbon reforming reaction.
Specifically, compared with an existing fixed-bed reactor, the structure of the micro channel reactor is advantageous in maximizing the performance of a catalyst by exchanging materials and heat in an effective manner. That is the reason such a micro channel reactor is evaluated as being fit to a hydrogen supplying apparatus for a small-sized fuel cell, a gas to liquid (GTL) process for producing synthetic petroleum using natural gas, a GTL-FPSO (Floating Production Storage and Offloading) process that is applicable to a marine environment, a petrochemical process, a fine chemistry process, an energy environment process, and the like.
For example, a unit reactor acting as a hydrogen generator in a micro channel reactor includes a micro channel having a minute width through which various fluids flow to expedite a reaction, and the micro channel is fabricated by an LIGA method that applies fine machining, chemical etching, X-ray etching, plating, etc., to a surface of a metal thin film together.
In aspects of catalytic reactions and heat exchange, it is preferable that the micro channel has a narrow width and a relatively deep depth with respect to the width. A plurality of micro channel thin films each having a micro channel are stacked on each other to increase the capacities of unit reactors so that the fluid supplied to the reactor is distributed and flows to the micro channels of the thin films of the reactor.
As mentioned above briefly, such a reactor is useful for a fuel reforming apparatus for a small-sized fuel cell which converts chemical energy produced by a chemical reaction between a fuel, i.e., hydrogen and an oxidizer, i.e., oxygen to electrical energy and which is common to a general chemical battery in utilizing in an oxidation-reduction reaction but is different from a chemical battery accompanied by a cell reaction in a closed system. That is, the fuel cell is a chemical free high-performance generation apparatus that continuously transfers reaction products, i.e., water and electricity to the outside of a system while a reactant is continuously supplied from the outside.
The fuel cell is applicable to an electricity supply system in various fields. In particular, studies on fuel cells are being actively carried out to apply the fuel cells to power sources that replace existing secondary batteries in the field of small-sized electronic device, but there are difficulties in keeping, storing, and supplying hydrogen used for fuels.
That is, while it is necessary to supply a fuel, i.e., hydrogen in order to operate a fuel cell, a large capacity storage tank that needs a considerable caution when dealing with the storage tank is required to store and use hydrogen.
Thus, it is preferable that a liquefied hydrocarbon material is reformed to obtain hydrogen which is used for a fuel. In particular, it is necessary to develop a compact fuel reforming apparatus to minimize the fuel cell. Furthermore, a compact GTL technology in which a required volume is reduced to 90% as compared with that of an existing GTL process is necessary to develop a small- or middle-sized offshore stranded gas field by making the GTL process compact, especially to develop a GTO-FPSO technology utilizing the compact GTL technology.
The structure of a general micro channel reactor is realized by stacking thin films used for unit reactors and fluid passage blocking plates together. In such a micro channel reactor, heat of catalytic combustion is effectively transferred to the unit reactors when a catalytic reaction is performed with a structure in which a reforming reaction fluid and a catalytic combustion fluid are mixed, making it possible to enhance the efficiency of the entire reactor and to prevent the flow of the fluid from being divided. As a result, there occurs no problem of dividing and distributing the flux of the fluid.
Anna Lee Tonkovich et al. discloses a fine passage metal reactor that has a combustion region of hydrocarbon, a heat absorbing layer using the heat of the combustion region and being adjacent to the combustion region, and a heat exchanging region (U.S. Patent Application Publication No. 2004/0033455 A1).
Ehrfeld Wolfgang of Germany discloses a structure of a fine passage heat exchanger using metal thin films in which heat is produced through combustion of hydrocarbon and an endothermic reaction is performed by the heat.
Meanwhile, a constant temperature is required within a reactor to perform a catalytic reaction in a general micro channel reactor and it is then important for a distributor to uniformly distribute a reactant to a catalyst.
Even if a reactant passes through a micro channel, since a product produced at a front portion (a upstream side of the channel) where the reactant is supplied to the reactor, i.e., a product produced by the reaction with the reactant and having a composition different from that of the reactant flows to be mixed with the reactant, the reaction over a catalyst is not smoothly performed at the rear of the micro channel, resulting in a temperature difference between the front and rear sides of the reactor.
Accordingly, local heat of combustion is caused even in a reactor having fine passages at a position where a reactant is introduced, hampering uniformity of temperature of the reactor. As a result, non-uniformity is caused in the combustion catalyst or the heated portion, deteriorating the activity of the catalyst.
The above-described technology is disclosed in U.S. Pat. No. 6,159,434 and Korean Patent Application Publication No. 2003-28829. In the patents, since a temperature/heat transfer control medium does not exist between unit reactors, it is difficult to control the temperatures of the reactors which is necessary for an effective chemical reaction.
In order to solve the problem, Korean Patent No. 599382 and Korean Patent No. 816361 suggested that a uniform contact should be induced between a reactant and a catalyst and a contact area should be increased by providing thin film distributing plates.
Meanwhile, since the reactant passes by the distributing plates irrespective of the flux of the reactant, it is difficult for the reactant to be transferred while the reactant is being transferred from the front side of the reactor to the catalyst through holes toward the rear side of the reactor.
Moreover, when the fluid flux of a reactant is large, a large pressure is applied to the outlet side of the reactor, in which case a larger pressure is applied due to collision between a reactant introduced from the inlet side of the reactor and a product produced with the reactor, influencing the entire flow of reaction. On the other hand, when the fluid flux of a reactant is small, the gas flows slowly, making it difficult to distribute the reactant.
In order to solve the above-mentioned problem, a 3D fine channel technology of forming passages vertically between micro channels has been suggested.
In Korean Patent Nos. 585374, 594185, and 646375, micro channels formed in plates of a micro heat exchanger have the form of vertical pipes and have a mixing space where fluid flows can be mixed. In the patents, heat can be efficiently transferred by mixing the fluids within 3D micro channels that generate vortices, i.e., secondary flows when the fluid flowing along the channels.
However, in order to achieve the object, the patents require a fine channel section having a 3D shape with respect to forward direction of fluid and having a plurality of minute through-holes, a discharge opening, a continuously formed supply opening, fine channel plates, and blocking plates where reaction sections and black plates are stacked and are accompanied by high costs for manufacturing a fine channel reactor, which is not economical.